Fluid machine and refrigeration cycle apparatus

ABSTRACT

A fluid machine ( 8 A) includes an expander ( 4 ) having an expander suction port ( 4   a ) and an expander discharge port ( 4   b ), a compressor ( 6 ) having a compressor suction port ( 6   a ) and a compressor discharge port ( 6   b ), and a shaft ( 81 ) coupling the expander ( 4 ) to the compressor ( 6 ). The expander suction port ( 4   a ) and the compressor suction port ( 4   a ) are opened and closed as the shaft ( 81 ) rotates. The expander suction port ( 4   a ) is opened during a period of time when the compressor suction port ( 6   a ) is closed, and the compressor suction port ( 6   a ) is opened and maintained out of communication with the compressor discharge port ( 6   b ) during a period of time when the expander suction port ( 4   a ) is closed.

TECHNICAL FIELD

The present invention relates to a fluid machine used for water heaters, air-conditioners, etc, and a refrigeration cycle apparatus using the fluid machine.

BACKGROUND ART

Conventionally, there have been known fluid machines in which an expander and a compressor are coupled to each other by a shaft and the compressor is driven by the power recovered from a working fluid expanding in the expander. For example, Patent Literature 1 discloses a fluid machine 100 shown in FIG. 12.

As shown in FIG. 12, an expander 110 and a compressor 120 are coupled to each other by a shaft 101 in the fluid machine 100. Both of the expander 110 and the compressor 120 are rotary type. The shaft 101 has a first eccentric portion 102 for the expander 110 and a second eccentric portion 103 for the compressor 120.

As shown in FIG. 13, the expander 110 has an expander piston 112 into which the first eccentric portion 102 of the shaft 101 is fitted, and an expander cylinder 111 accommodating the expander piston 112. A crescent-shaped expander working chamber 113 is formed between an inner circumferential surface of the expander cylinder 111 and an outer circumferential surface of the expander piston 112. The expander working chamber 113 is partitioned into a suction side space and a discharge side space by an expander partition member 114. The expander partition member 114 is integrated with the expander piston 112. A columnar shoe 117 supporting reciprocably the expander partition member 114 is provided rotatably to the expander cylinder 111. That is, the expander piston 112 swings taking the center of the shoe 117 as the pivot point while changing the distance between the supporting point and itself.

The expander cylinder 111 is provided with a suction port 110 a through which a working fluid is introduced into the expander working chamber 113, and a discharge port 110 b through which the working fluid is discharged from the expander working chamber 113. The suction port 110 a is, at a specified timing, brought into communication with the expander working chamber 113 through a communication port 115 formed in the shoe 117 and a communication groove 116 formed in the expander partition member 113. That is, the shoe 117 and the expander partition member 113 constitute a drawing control mechanism for opening and closing the suction port 110 a as the shaft 101 rotates. The timing at which the suction port 110 a is opened (in communication with the expander working chamber 113) is a period of time from when the expander piston 112 is at a top dead center at which it retracts the expander partition member 114 most until the expander piston 112 rotates about 140° from the top dead center.

As shown in FIG. 14, the compressor 120 has a compressor piston 122, composed of roller bearings, into which the second eccentric portion 103 of the shaft 101 is fitted, and a compressor cylinder 121 accommodating the compressor piston 122. A crescent-shaped compressor working chamber 123 is formed between an inner circumferential surface of the compressor cylinder 121 and an outer circumferential surface of the compressor piston 122. The compressor working chamber 123 is partitioned into a suction side space and a discharge side space by a compressor partition member 124. The compressor partition member 114 is pressed against the compressor piston 122 by a spring.

The compressor cylinder 121 is provided with a suction port 120 a through which the working fluid is introduced into the compressor working chamber 123. A closing member adjacent to the compressor cylinder 121 and the compressor piston 122 is provided with a discharge port 120 b through which the working fluid is discharged from the compressor working chamber 113. The suction port 120 a opens on the inner circumferential surface of the compressor cylinder 121. The suction port 120 a is closed by the compressor piston 122 only when a sliding point of the compressor piston 122 sliding on the inner circumferential surface of the compressor cylinder 121 is present on the suction port 120 a.

Patent Literature 1 also discloses a refrigeration cycle apparatus 200 shown in FIG. 15 using the fluid machine 100. The refrigeration cycle apparatus 200 has a configuration in which the compressor 120 of the fluid machine 100 increases preliminarily the pressure of the working fluid to be drawn into a main compressor 210. The main compressor 210, a radiator 220, the expander 110, an evaporator 230, and the compressor 120 are connected in this order by a flow passage so as to constitute a working fluid circuit.

CITATION LIST Patent Literature

-   PTL 1: JP 2004-324595 A

SUMMARY OF INVENTION Technical Problem

The fluid machine 100 includes no driving means such as a motor, and is expected to self-start owing to the pressure of the working fluid in the refrigeration cycle apparatus 200 as shown in FIG. 15. That is, starting the main compressor 210 allows the high pressure working fluid to flow into the suction side space of the expander working chamber 113 of the expander 110. This causes a pressure difference between the suction side space and the discharge side space of the expander working chamber 113, and this pressure difference applies a torque to the shaft 101 to start the fluid machine 100.

However, when the fluid machine 100 is stopped in the state where the suction port 110 a of the expander 110 is closed, the high pressure working fluid cannot flow into the expander working chamber 113 and thus no torque for rotating the shaft 101 is generated.

In contrast, the inventors of the present invention arrived at, prior to the present invention, an idea of guiding, at the time of starting, the high pressure working fluid discharged from the main compressor also to the compressor of the fluid machine to apply a torque to the shaft also in the compressor. That is, a bypass passage that links a high pressure flow passage between the main compressor and the radiator or between the radiator and the expander to a low pressure passage between the evaporator and the compressor is provided so as to allow the high pressure working fluid to flow also into the suction side space of the compressor working chamber of the compressor at the time of starting. Thereby, a pressure difference is generated also between the suction side space and the discharge side space of the compressor working chamber. As a result, a torque can be applied to the shaft also in the compressor.

However, even when the above-mentioned technique is applied to the fluid machine 100 disclosed in Patent Literature 1, no torque for rotating the shaft 101 is generated yet in some cases. The reason is as follows.

In the fluid machine 100 disclosed in Patent Literature 1, the position of the expander partition member 114 and the position of the compressor partition member 124 coincide with each other in the axial direction of the shaft 101, and an eccentric orientation of the first eccentric portion 102 is deviated 180° from an eccentric orientation of the second eccentric portion 103. Moreover, in the compressor 120, the suction port 120 a is in communication with the discharge port 120 b through the compressor working chamber 123 until the sliding point of the compressor piston 121 reaches the suction port 120 a after passing the discharge port 120 b.

Thus, with the rotation angle of the shaft 101 when the expander piston 112 is present at the top dead center being defined as 0°, the working fluid can flow into the suction side space of the expander working chamber 113 in the expander 110 when the rotation angle of the shaft 101 is in the range from 0° to about 140°. On the other hand, in the compressor 120, although the suction port 120 a of the compressor 120 is closed by the compressor piston 122 when the rotation angle of the shaft 101 is in the range from about 190° to about 200°, the working fluid can flow into the suction side space of the compressor working chamber 123 when the rotation angle of the shaft 101 is out of this range.

However, when the rotation angle of the shaft 101 is in the range from about 190° to about 200°, both of the expander suction port 110 a and the compressor suction port 120 a are closed, and the torque for rotating the shaft 110 is generated neither in the expander 110 nor in the compressor 120. Moreover, when the rotation angle of the shaft 101 is in the range from about 180°, at which the sliding point of the compressor piston 121 passes the discharge port 120 b, to about 190°, at which the sliding point reaches the suction port 120 a, the suction port 120 a is in communication with the discharge port 120 b through the compressor working chamber 123 as described above and the working fluid that has flowed into the compressor working chamber 123 through the suction port 120 a is discharged through the discharge port 120 b. Furthermore, the suction port 110 a of the expander 110 is closed during that time. Therefore, when the fluid machine 100 is stopped in the state where the rotation angle of the shaft is between about 180° and about 200°, the torque for rotating the shaft 101 owing to the pressure of the working fluid cannot be generated and the fluid machine 100 cannot self-start.

In view of the foregoing, the present invention is intended to provide a fluid machine that can self-start owing to the pressure of the working fluid no matter in what state it is stopped, and a refrigeration cycle apparatus using the fluid machine.

Solution to Problem

In order to solve the above-mentioned problems, the present invention provides a fluid machine including: an expander that expands a working fluid drawn through an expander suction port and discharges the working fluid through an expander discharge port so as to recover power from the working fluid; a compressor that increases a pressure of the working fluid drawn through a compressor suction port and discharges the working fluid through a compressor discharge port; and a shaft that couples the expander to the compressor so that the compressor is driven by the power recovered by the expander. The expander suction port and the compressor suction port are opened and closed as the shaft rotates. The expander suction port is opened during a period of time when the compressor suction port is closed, and the compressor suction port is opened and maintained out of communication with the compressor discharge port during a period of time when the expander suction port is closed.

The present invention also provides a refrigeration cycle apparatus using the fluid machine, including: a working fluid circuit through which a working fluid circulates, the working fluid circuit including a main compressor for compressing the working fluid, a radiator for radiating heat from the compressed working fluid, the expander for expanding the working fluid that has flowed out of the radiator, an evaporator for evaporating the expanded working fluid, and the compressor for increasing a pressure of the working fluid that has flowed out of the evaporator and supplying the working fluid to the main compressor; and a bypass passage linking a portion between the main compressor and the radiator or a portion between the radiator and the expander to a portion between the evaporator and the compressor in the working fluid circuit.

Advantageous Effects of Invention

According to the above-mentioned configuration, the working fluid can always flow into one or both of the suction side space of the expander working chamber and the suction side space of the compressor working chamber. In the compressor working chamber, the working fluid that has flowed therein is prevented from being discharged through the compressor discharge port. Therefore, the fluid machine can self-start owing to the pressure of the working fluid no matter in what state it is stopped.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus using a fluid machine according to Embodiment 1 of the present invention.

FIG. 2 is a vertical cross-sectional view of the fluid machine according to Embodiment 1 of the present invention.

FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2.

FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 2.

FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 2.

FIGS. 6A to 6C each are a diagram illustrating the operating principle of the fluid machine according to Embodiment 1 of the present invention.

FIGS. 7A to 7C each are a diagram illustrating the operating principle of the fluid machine according to Embodiment 1 of the present invention.

FIG. 8 is a vertical cross-sectional view of a fluid machine according to Embodiment 2 of the present invention.

FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. 8.

FIGS. 10A to 10C each are a diagram illustrating the operating principle of the fluid machine according to Embodiment 2 of the present invention.

FIGS. 11A to 11C each are a diagram illustrating the operating principle of the fluid machine according to Embodiment 2 of the present invention.

FIG. 12 is a vertical cross-sectional view of a conventional fluid machine.

FIG. 13 is a cross-sectional view taken along the line A-A in FIG. 12.

FIG. 14 is a cross-sectional view taken along the line B-B in FIG. 12.

FIG. 15 is a configuration diagram of a refrigeration cycle using the fluid machine shown in FIG. 12.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention, however, is not limited to the following embodiments.

Embodiment 1 Configuration of Refrigeration Cycle Apparatus

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus 1 using a fluid machine 8A according to Embodiment 1 of the present invention. The refrigeration cycle apparatus 1 is provided with a working fluid circuit 7 through which a working fluid (refrigerant) circulates. The working fluid circuit 7 includes a main compressor 2, a radiator 3, an expander 4, an evaporator 5, and a compressor 6 as a sub compressor. These components 2 to 6 are connected in this order by a first to fifth flow passages (pipes) 7 a to 7 e. As the working fluid, carbon dioxide and chlorofluorocarbon alternative can be used, for example.

The main compressor 2 has, in a single closed casing 2 c holding a lubricating oil, a compression mechanism 2 a and a motor 2 b for driving the compression mechanism 2 a. The main compressor 2 compresses the working fluid at high temperature and high pressure. As the main compressor 2, a scroll type compressor and a rotary type compressor can be used, for example. A discharge mouth of the main compressor 2 is connected to an inlet of the radiator 3 through the first flow passage 7 a.

The radiator 3 radiates heat from the high temperature, high pressure working fluid compressed in the main compressor 2 to cool the working fluid. An outlet of the radiator 3 is connected to a suction mouth of the expander 4 through the second flow passage 7 b.

The expander 4 expands the middle temperature, high pressure working fluid that has flowed out of the radiator 3 and converts the expansion energy of the working fluid into mechanical energy, thereby recovering power from the working fluid. In the present embodiment, the expander 4 is a rotary type expander (details will be described later). A discharge mouth of the expander 4 is connected to an inlet of the evaporator 5 through the third flow passage 7 c.

The evaporator 5 heats the low temperature, low pressure working fluid that has been expanded in the expander 4 to evaporate the working fluid. An outlet of the evaporator 5 is connected to a suction mouth of the compressor 6 through the fourth flow passage 7 d.

The compressor 6 increases preliminary the pressure of the middle temperature, low pressure working fluid that has flowed out of the evaporator 5 and supplies the working fluid to the main compressor 2. In the present embodiment, the compressor 6 is a rotary type compressor (details will be described later). A discharge mouth of the compressor 6 is connected to a suction mouth of the main compressor 2 through the fifth flow passage 7 e.

The expander 4 and the compressor 6 are disposed in a single closed casing 80 holding a lubricating oil, while being coupled to each other by a shaft 81, to constitute the fluid machine 8A. That is, the power recovered by the expander 4 is transferred to the compressor 6 via the shaft 81, thereby driving the compressor 6.

The refrigeration cycle apparatus 1 shown in FIG. 1 further is provided with a first bypass passage 91 with its both ends being connected to the working fluid circuit 7 so as to bypass the evaporator 5 and the compressor 6, and a second bypass passage (corresponding to a bypass passage of the present invention) 93 with its both ends being connected to the working fluid circuit 7 so as to bypass the expander 4 and the evaporator 5. The first bypass passage 91 has a first bypass valve 92 for controlling the flow of the working fluid in the first bypass passage 91. The second bypass passage 93 has a second bypass valve 94 for controlling the flow of the working fluid in the second bypass passage 93.

The first bypass passage 91 links the third flow passage 7 c for guiding the working fluid from the discharge mouth of the expander 4 to the inlet of the evaporator 5 to the fifth flow passage 7 e for guiding the working fluid from the discharge mouth of the compressor 6 to the suction mouth of the main compressor 2. That is, the first bypass passage 91 is a flow passage that allows the working fluid discharged from the expander 4 to bypass the evaporator 5 and the compressor 6 so as to be drawn directly into the main compressor 2. In the present embodiment, a check valve is used as the first bypass valve 92. However, the first bypass valve 92 is not limited to this, and an opening and closing valve or a three-way valve may be used.

The first bypass valve 92 allows the working fluid to flow through the first bypass passage 91 when the working fluid in the first bypass passage 91 downstream (outlet side) of the first bypass valve 92 has a lower pressure than that of the working fluid in the first bypass passage 91 upstream (inlet side) of the first bypass valve 92. In the opposite case, the first bypass valve 92 prohibits the working fluid from flowing through the first bypass passage 91. That is, the working fluid flows from the third flow passage 7 c into the fifth flow passage 7 e through the first bypass passage 91 when the working fluid in the fifth flow passage 7 e between the discharge mouth of the compressor 6 and the suction mouth of the main compressor 2 has a lower pressure than that of the working fluid in the flow passage (the third flow passage 7 c, the evaporator 5, and the fourth flow passage 7 d) between the discharge mouth of the expander 4 and the suction mouth of the compressor 6.

The second bypass passage 93 links the second flow passage 7 b for guiding the working fluid from the outlet of the radiator 3 to the suction mouth of the expander 4 to the fourth flow passage 7 d for guiding the working fluid from the outlet of the evaporator 5 to the suction mouth of the compressor 6. That is, the second bypass passage 93 is a flow passage that allows the high pressure working fluid that has flowed out of the radiator 3 to bypass the expander 4 and the evaporator 5 so as to be drawn directly into the compressor 6. In the present embodiment, an opening and closing valve is used as the second bypass valve 94. However, the second bypass valve 94 is not limited to this, and a three-way valve may be used. Moreover, the second bypass passage 92 has only to be a flow passage that allows the high pressure working fluid to be drawn directly into the compressor 6. The second bypass passage 92 may link the first flow passage 7 a for guiding the working fluid from the discharge mouth of the main compressor 2 to the inlet of the radiator 3 to the fourth flow passage 7 d.

The second bypass valve 94 is opened in the start control, and thereby the high pressure working fluid that has flowed out of the radiator 3 flows from the second flow passage 7 b into the fourth flow passage 7 d through the second bypass passage 93.

In the refrigeration cycle apparatus 1 shown in FIG. 1, a compressor upstream valve 71 for controlling the flow of the working fluid in the fourth flow passage 7 d is provided to the fourth flow passage 7 d between the outlet of the evaporator 5 and the position at which a downstream end of the second bypass passage 93 is connected to the fourth flow passage 7 d. In the present embodiment, an opening and closing valve is used as the compressor upstream valve 71. The compressor upstream valve 71 is closed in the start control so as to prevent the working fluid from flowing from the evaporator 5 into the compressor 6 and prevent the working fluid that has flowed into the fourth flow passage 7 d through the second bypass passage 93 from flowing into the evaporator 5.

The second bypass valve 94 and the compressor upstream valve 71 are controlled by a controller that is not shown. Moreover, the refrigeration cycle apparatus 1 is provided, although not shown, with a start detection means for detecting that the compressor 6 is started. When the compressor 6 is started, a detection signal is transmitted from the start detection means to the controller. As the start detection means, it is possible to use a method, with a thermocouple provided to the third flow passage 7 c on a discharge side of the expander 4, to measure the temperature of the working fluid in the third flow passage 7 c, for example.

<Operation of Refrigeration Cycle Apparatus>

The refrigeration cycle apparatus 1 performs the start control first, and then initiates steady operation. In the refrigeration cycle apparatus 1, the pressure of the working fluid in the working fluid circuit 7 is approximately uniform when the refrigeration cycle apparatus 1 is in standby state (stopped state) for operation.

In the start control, the second bypass valve 94 is opened and the compressor upstream valve 71 is closed first. Thereby, the second bypass passage 93 is opened through and the fourth flow passage 7 d is blocked between the outlet of the evaporator 5 and the downstream end of the second bypass passage 93. Subsequently, the main compressor 2 is started and the working fluid in the fifth flow passage 7 e and the working fluid in the first bypass passage 91 downstream of the first bypass valve 92 are drawn into the main compressor 2.

When the drawing of the working fluid into the main compressor 2 begins, the pressures of the working fluid in the fifth flow passage 7 e and the working fluid in the first bypass passage 91 downstream of the first bypass valve 92 are lowered. Thereby, the first bypass valve 92, which is a check valve, is opened, and the working fluid in the flow passage (the third flow passage 7 c, the evaporator 5, and a part of the fourth flow passage 7 d) from the discharge mouth of the expander 4 to the compressor upstream valve 71 flows into the first bypass passage 91. That is, the working fluid in the flow passage from the discharge mouth of the expander 4 to the compressor upstream valve 71 is drawn into the main compressor 2 together with the working fluid in the first bypass passage 9 and the working fluid in the fifth flow passage 7 e so as to be compressed and discharged into the first flow passage 7 a. As a result, the pressure of the working fluid in the first bypass passage 91 upstream of the first bypass valve 92 and the working fluid in the flow passage from the discharge mouth of the expander 4 to the compressor upstream valve 71 are lowered.

In contrast, the pressure of the working fluid in the flow passage (the first flow passage 7 a, the radiator 3, and the second flow passage 7 b) from the discharge mouth of the main compressor 2 to the suction mouth of the expander 4 is increased because the working fluid drawn into the main compressor 2 is compressed and discharged. Moreover, since the second bypass valve 94 is opened and the compressor upstream valve 71 is closed in the start control, the working fluid in the flow passage from the discharge mouth of the main compressor 2 to the suction mouth of the expander 4 flows, through the second bypass passage 93, also into a portion of the fourth flow passage 7 d between the compressor upstream valve 71 and the suction mouth of the compressor 6. This increases the pressure of the working fluid in the flow passage (a part of the fourth flow passage 7 d) from the compressor upstream valve 71 to the suction mouth of the compressor 6.

Therefore, high pressure-low pressure differences occur between the working fluid (high pressure) in the flow passage (the second flow passage 7 b) on a side of the suction mouth of the expander 4 and the working fluid (low pressure) in the flow passage (the third flow passage 7 c) on a side of the discharge mouth of the expander 4, and between the working fluid (high pressure) in the flow passage (a part of the fourth flow passage 7 d) on a side of the suction mouth of the compressor 6 and the working fluid (low pressure) in the flow passage (the fifth flow passage 7 e) on a side of the discharge mouth of the compressor 6, respectively. These high pressure-low pressure differences between the working fluids act on the expander 4 and the compressor 6, respectively, making it possible for the fluid machine 8A to self-start easily.

When the above-mentioned start detection means detects that the compressor 6 is started, the second bypass valve 94 is closed and the compressor upstream valve 71 is opened. Thereby, the second bypass passage 93 is blocked and the fourth flow passage 7 d is opened through. Then the refrigeration cycle apparatus 1 ends the start control and shifts to the steady operation in which the working fluid circulates through the working fluid circuit 7.

During the steady operation, the working fluid in the fourth flow passage 7 d and the working fluid in the second bypass passage 93 downstream of the second bypass valve 94 are drawn into the compressor 6 and its pressure is increased, and the working fluid is discharged into the fifth flow passage 7 e. Thereby, the working fluid in the fifth flow passage 7 e and the working fluid in the first bypass passage 91 downstream of the first bypass valve 92 have a higher pressure than the pressure of the working fluid in the flow passage (the third flow passage 7 c, the evaporator 5, and the fourth flow passage 7 d) from the discharge mouth of the expander 4 to the suction mouth of the compressor 6 and the pressure of the working fluid in the first bypass passage 91 upstream of the first bypass valve 92. Thus, the first bypass valve 92, which is a check valve, is closed. During the steady operation, the working fluid in the fifth flow passage 7 e and the working fluid in the first bypass passage 91 downstream of the first bypass valve 92 have a high pressure as in the case above, and thus the first bypass valve 92 remains closed. Thereby, the working fluid during the steady operation circulates through the working fluid circuit 7.

<Configuration of Fluid Machine>

Next, the configuration of the fluid machine 8A will be described in detail. FIG. 2 is a vertical cross-sectional view of the fluid machine 8A. FIGS. 3 to 5 are transverse cross-sectional views of the fluid machine 8A taken along the lines III-III to V-V in FIG. 2, respectively. In FIGS. 3 to 5, the closed casing 80 is omitted.

As described above, the fluid machine 8A is a power recovering system in which the expander 4 and the compressor 6 are coupled to each other by the shaft 81 so that the power recovered by the expander 4 drives the compressor 6. In the present embodiment, the shaft 81 extends in a vertical direction, the expander 4 is disposed at a lower part in the closed casing 80, and the compressor 6 is disposed at an upper part in the closed casing 80. However, the positional relationship between the expander 4 and the compressor 6 may be vertically opposite. The shaft 81 may extend in a lateral direction so that the expander 4 and the compressor 6 are aligned in the lateral direction. The closed casing 80 is filled with the lubricating oil to an extent that the oil level is present above the compressor 6.

1) Shaft

The shaft 81 has a first eccentric portion 81 b for the expander 4 and a second eccentric portion 81 c for the compressor 6 as eccentric portions, each having a central axis at a location away from the axial center of the shaft 81. An oil supply passage 81 a that penetrates through the shaft 81 in the axial direction and that opens on an outer circumferential surface of the first eccentric portion 81 b, an outer circumferential surface of the second eccentric portion 81 c, etc. is formed in the shaft 81. Through the oil supply passage 81 a, the lubricating oil in the closed casing 80 is supplied to the sliding parts, etc. of the expander 4 and the compressor 6.

2) Expander

As described above, the expander 4 is a rotary type expander in the present embodiment. However, the expander 4 is not limited to the rotary type expander and may be a scroll type expander or another type of expander. The expander 4 expands the working fluid drawn through the expander suction port 4 a and discharges the working fluid through the expander discharge port 4 b so as to recover power from the working fluid.

Specifically, as shown in FIG. 4, the expander 4 has an expander piston 42 into which the first eccentric portion 81 b of the shaft 81 is fitted, and an expander cylinder 41 accommodating the expander piston 42. The expander cylinder 41 has an inner circumferential surface forming a cylindrical surface whose central axis coincides with the axial center of the shaft 81. The expander piston 42 performs an eccentric rotational motion along the inner circumferential surface of the expander cylinder 41 as the shaft 81 rotates. That is, a crescent-shaped expander working chamber 43 is formed between the inner circumferential surface of the expander cylinder 41 and an outer circumferential surface of the expander piston 42.

The expander working chamber 43 is partitioned into a suction side space 43 a and a discharge side space 43 b by an expander partition member 44. The expander suction port 4 a opens to a portion of the suction side space 43 a adjacent to the expander partition member 44. The expander discharge port 4 b opens to a portion of the discharge side space 43 b adjacent to the expander partition member 44.

The expander partition member 44 has a plate-like shape and is inserted reciprocably in a groove 41 a formed in the expander cylinder 41. The groove 41 a opens to the expander working chamber 43, on a straight line passing the axial center of the shaft 81. A biasing means 45 for pressing the expander partition member 44 against the outer circumferential surface of the expander piston 42 is disposed between a bottom of the groove 41 a and the expander partition member 44.

The biasing means 45 can be composed of a compression coil spring, for example. The biasing means 45 may be a so-called gas spring configured by making a back space between a rear edge of the expander partition member 44 and the bottom of the groove 41 a a closed space. The biasing means 45 may be composed of two or more types of springs, such as the compression coil spring and the gas spring, of course. The expander piston 42 and the expander partition member 44 may be integrated with each other, without the biasing means 45 being provided.

As shown in FIG. 2, the expander 4 has a first closing member (inner closing member) 49 for closing the expander working chamber 43 from a side of the compressor 6, a second closing member (outer closing member) 46 for closing the expander working chamber 43 from a side opposite to the compressor 6, and a bearing member 47 disposed below the second closing member 46.

The bearing member 47 is fixed to an inner circumferential surface of the closed casing 80 and supports rotatably a lower part of the shaft 81. The second closing member 46, the expander cylinder 41, and the first closing member 49 are stacked in this order on the bearing member 47. A suction pipe 82 and a discharge pipe 83 penetrating through the closed casing 80 are connected to the bearing member 47.

The first closing member 49 and the second closing member 46 each have a disc shape that is flattened in the axial direction of the shaft 81. The shaft 81 penetrates through the centers of the first closing member 49 and the second closing member 46. In the present embodiment, the expander suction port 4 a is provided in the second closing member 46 and the expander discharge port 4 b is provided in the first closing member 49 and the expander cylinder 41.

A circular recessed portion 46 a whose center coincides with the axial center of the shaft 81 is provided on a lower surface of the second closing member 46. The expander suction port 4 a penetrates through the second closing member 46 in the axial direction of the shaft 81 so as to extend straightly from an upper surface of the second closing member 46 to a bottom surface of the recessed portion 46 a. The expander suction port 4 a is in communication with the suction pipe 82 through a suction space inside the recessed portion 46 a and a suction passage 47 a formed in the bearing member 47. That is, the high pressure working fluid from the second flow passage 7 b shown in FIG. 1 is guided from the expander suction port 4 a to the suction side space 43 a of the expander working chamber 43 through the suction pipe 82, the suction passage 47 a, and the suction space inside the recessed portion 46 a.

On the other hand, as shown in FIG. 4, the expander discharge port 4 b is constructed of a vertical groove 41 b recessed radially outward and formed in the inner circumferential surface of the expander cylinder 41, and a lateral groove 49 a formed in a lower surface of the first closing member 49 so as to extend radially outward from a position corresponding to the vertical groove 41 b. An outer end of the expander discharge port 4 b is in communication with the discharge pipe 83 through a discharge passage 4 c formed so as to extend across the expander cylinder 41, the second closing member 46, and the bearing member 47. That is, the working fluid in the discharge side space 43 b of the expander working chamber 43 is discharged into the third flow passage 7 c shown in FIG. 1 through the expander discharge port 4 b, the discharge passage 4 c, and the discharge pipe 83.

Further, inside the recessed portion 46 a, a rotor plate 48 is disposed as a drawing control mechanism for opening and closing the expander suction port 4 a as the shaft 81 rotates. The rotor plate 48 is attached to the shaft 81 so as to rotate while being in contact with the bottom surface of the recessed portion 46 a.

As shown in FIG. 4, the expander suction port 4 a extends in an arc shape from a vicinity of the expander partition member 44 along the inner circumferential surface of the expander cylinder 41. As shown in FIG. 3, the rotor plate 48 has a large diameter portion 48 a for blocking the expander suction port 4 a and a small diameter portion 48 b for exposing the expander suction port 4 a.

In the present embodiment, the expander suction port 4 a is exposed partly or completely when the expander piston 41 rotates 140° from a top dead center, and the expander suction port 4 a is completely blocked by the large diameter portion 48 a anytime other than this period, according to the angle ranges and positions of the large diameter portion 48 a and the small diameter portion 48 b. Here, the top dead center refers to a location at which a sliding point of the expander piston 42 sliding on the inner circumferential surface of the expander cylinder 41 coincides with the expander partition member 44.

The configuration of the expander 4 can be inverted vertically. That is, the first closing member 49, the expander cylinder 41, the second closing member 46, the rotor plate 48, and the bearing member 47 may be disposed in this order from bottom to top so that the first closing member 49 serves as the outer closing member and the second closing member 46 serves as the inner closing member. In this case, the bearing member 47 may fit loosely around the shaft 81, and the first closing member 49 may have a function of supporting rotatably the lower part of the shaft 81.

3) Compressor

As described above, the compressor 6 is a rotary type compressor in the present embodiment. The compressor 6 increases the pressure of the working fluid drawn through the compressor suction port 6 a and discharges the working fluid through the compressor discharge port 6 b.

Specifically, as shown in FIG. 5, the compressor 6 has a compressor piston 62 into which the second eccentric portion 81 c of the shaft 81 is fitted, and a compressor cylinder 61 accommodating the compressor piston 62. The compressor cylinder 61 has an inner circumferential surface forming a cylindrical surface whose central axis coincides with the axial center of the shaft 81. The compressor piston 62 performs an eccentric rotational motion along the inner circumferential surface of the compressor cylinder 61 as the shaft 81 rotates. That is, a crescent-shaped compressor working chamber 63 is formed between the inner circumferential surface of the compressor cylinder 61 and an outer circumferential surfaces of the compressor piston 62.

The compressor working chamber 63 is partitioned into a suction side space 63 a and a discharge side space 63 b by an compressor partition member 64. The compressor suction port 6 a opens to a portion of the suction side space 63 a adjacent to the compressor partition member 64. The compressor discharge port 6 b opens to a portion of the discharge side space 63 b adjacent to the compressor partition member 64.

The compressor partition member 64 has a plate-like shape and is inserted reciprocably in a groove 61 a formed in the compressor cylinder 61. The groove 61 a opens to the compressor working chamber 63, on a straight line passing the axial center of the shaft 81. A biasing means 65 for pressing the compressor partition member 64 against the outer circumferential surface of the compressor piston 62 is disposed between a bottom of the groove 61 a and the compressor partition member 64.

The biasing means 65 can be composed of a compression coil spring, for example. The biasing means 65 may be a so-called gas spring configured by making a back space between a rear edge of the compressor partition member 64 and the bottom of the groove 61 a a closed space. The biasing means 65 may be composed of two or more types of springs, such as the compression coil spring and the gas spring, of course. The compressor piston 62 and the compressor partition member 64 may be integrated with each other, without the biasing means 65 being provided.

Moreover, as shown in FIG. 2, the compressor 6 has the first closing member (inner closing member) 49 for closing the compressor working chamber 63 from a side of the expander 4, a second closing member (outer closing member) 66 for closing the compressor working chamber 63 from a side opposite to the expander 4, and a cover member 67 disposed above the second closing member 46. That is, the expander 4 and the compressor 6 share the first closing member 49 in the present embodiment. However, the expander 4 and the compressor 6 may have the first closing members, respectively.

The second closing member 66 has a function as a bearing member for supporting rotatably an upper part of the shaft 81. The compressor cylinder 61, the second closing member 66, and the cover member 67 are stacked in this order on the first closing member 49. A suction pipe 84 penetrating through the closed casing 80 is connected to the compressor cylinder 61. A discharge pipe 85 penetrating through the closed casing 80 is connected to the second closing member 66.

The second closing member 66 has a disc shape that is flattened in the axial direction of the shaft 81. The shaft 81 penetrates through the center of the second closing member 66. The cover member 67 also has a disc shape that is flattened in the axial direction of the shaft 81. At the center of the cover member 67, an opening through which an upper end portion of the shaft 81 is exposed is provided. In the present embodiment, the compressor suction port 6 a is provided in the compressor cylinder 61 and the compressor discharge port 6 b is provided in the second closing member 66.

The compressor suction port 6 a penetrates laterally through the compressor cylinder 61. The compressor suction port 6 a opens approximately circularly on the inner circumferential surface of the compressor cylinder 61, and is in communication with the suction pipe 84. That is, the low pressure (high pressure during the start control) working fluid from the fourth flow passage 7 d shown in FIG. 1 is guided from the compressor suction port 6 a to the suction side space 63 a of the compressor working chamber 63 through the suction pipe 84.

Since the compressor suction port 6 a opens on the inner circumferential surface of the compressor cylinder 61, it is opened and closed by the compressor piston 62 as the shaft rotates. More specifically, the compressor suction port 6 a is closed by the compressor piston 62 only when the sliding point of the compressor piston 62 sliding on the inner circumferential surface of the compressor cylinder 61 is present on the compressor suction port 6 a, in other words, only when the compressor piston 62 rotates from the point of about 5° to the point of about 15°, with a top dead center (a location at which the sliding point of the compressor piston 62 coincides with the compressor partition member 64) being defined as 0°. In a strict sense, the compressor suction port 6 a is not completely closed by the compressor piston 62 because the inner circumferential surface of the compressor cylinder 61 and the outer circumferential surface of the compressor piston 62 have different diameters from each other. However, in this description, it is defined, as described above, that the compressor suction port 6 a is closed when the sliding point of the compressor piston 62 is present on the compressor suction port 6 a.

In contrast, a discharge chamber 66 a opening upward and closed by the cover member 67, and a discharge passage 66 b extending from the discharge chamber 66 a to the discharge pipe 85 are formed in the second closing member 66. The compressor discharge port 6 b has a circular section and penetrates through the second closing member 66 in the axial direction of the shaft 81 so as to extend straightly from a lower surface of the second closing member 66 to the discharge chamber 66 a. The compressor discharge port 6 b is in communication with the discharge pipe 85 through the discharge chamber 66 a and the discharge passage 66 b. That is, the working fluid in the discharge side space 63 b of the compressor working chamber 63 is discharged into the fifth flow passage 7 e shown in FIG. 1 through the compressor discharge port 6 b, the discharge chamber 66 a, the discharge passage 66 b, and the discharge pipe 85.

In the present embodiment, since the compressor discharge port 6 b is disposed at a location that allows it to be crossed by the inner circumferential surface of the compressor cylinder 61, the compressor discharge port 6 b is closed by the compressor piston 62 only when the sliding point of the compressor piston 62 is present on the compressor discharge port 6 b, in other words, only when the compressor piston 62 rotates from the point of about 345° to the point of about 355°, with the top dead center being defined as 0°. As in the case of the compressor suction port 6 a, the compressor discharge port 6 b is not completely closed by the compressor piston 62 in a strict sense. However, in this description, it is defined, as described above, that the compressor discharge port 6 b is closed when the sliding point of the compressor piston 62 is present on the compressor discharge port 6 b.

A discharge valve 68 that, by being deformed elastically, opens and closes automatically the compressor discharge port 6 b owing to the pressure of the discharge side space 63 b of the compressor working chamber 63 is disposed in the discharge chamber 66 a.

Forming the compressor suction port 6 a as described above makes it possible to reduce the passage resistance of the working fluid flowing into the compressor working chamber 63 and suppress the decrease in the pressure of the working fluid to be drawn into the compressor 6. Moreover, forming the compressor discharge port 6 b as described above makes it possible to simplify the structure of the compressor 6, reduce the passage resistance of the working fluid flowing out of the compressor working chamber 63, and suppress the decrease in the pressure of the working fluid to be discharged from the compressor 6.

The configuration of the compressor 6 can be inverted vertically. That is, the cover member 67, the second closing member 66, the compressor cylinder 61, and the first closing member 49 may be disposed in this order from bottom to top so that the first closing member 49 serves as the outer closing member and the second closing member 66 serves as the inner closing member. In this case, the second closing member 66 may fit loosely around the shaft 81, and the first closing member 49 may have a function of supporting rotatably the upper part of the shaft 81.

4) Correlation

The fluid machine 8A is configured so that the expander suction port 6 a is opened during a period of time when the compressor suction port 6 a is closed, and the compressor suction port 6 a is opened and maintained out of communication with the compressor discharge port 6 b during a period of time when the expander suction port 6 a is closed. Specifically, the shaft 81, the expander 4, and the compressor 6 are configured so that the compressor piston 62 passes the top dead center within a period of time when the expander suction port 6 a is opened.

In order to achieve this configuration, Formula 1 below preferably is satisfied where, when a rotation direction of the shaft 81 is defined as positive, βc (−180°<βc≦180°) indicates a phase difference of an eccentric orientation of the second eccentric portion 81 c with respect to an eccentric orientation of the first eccentric portion 81 b, βv (−180°<βc≦180°) indicates a phase difference of a position of the compressor partition member 64 with respect to a position of the expander partition member 44, and further θo indicates a rotation angle of the shaft during the period of time when the expander suction port 6 a is opened.

0.25θo≦βv−βc≦0.75θo  (Formula 1)

In the present embodiment, as shown in FIG. 4 and FIG. 5, the position of the expander partition member 44 and the position of the compressor partition member 64 coincide with each other in the axial direction of the shaft 81, and the eccentric orientation of the second eccentric portion 81 c is deviated −90° from the eccentric orientation of the first eccentric portion 81 b. That is, βc=−90°, βv=0°, and βv−βc=90°. Moreover, due to the shape of the rotor plate 48 as described above, θo=about 140°, leading to 0.25θo≈35° and 0.75θo105°, which satisfies Formula 1.

The present invention is not limited to this. For example, it may be configured so that the first eccentric portion 81 b and the second eccentric portion 81 c are eccentric in the same direction and the position of the expander partition member 44 and the position of the compressor partition member 64 are deviated from each other within a range that satisfies Formula 1, or so that deviations occur in terms both of the eccentric orientation and the position of the partition members within ranges that satisfy Formula 1.

<Operation of Fluid Machine>

Next, the operation of the fluid machine 8A during the steady operation will be described with reference to FIGS. 6A to 6C and FIGS. 7A to 7C. In these figures, the rotation angle θ of the shaft 81 when the expander piston 42 is present at the top dead center is defined as 0°.

First, the operation of the expander 4 will be explained. As shown in FIGS. 6A to 6C, the shaft 81 rotates from θ=0° and the rotor plate 48 rotates synchronously with it, so that the expander suction port 4 a starts being exposed out of the rotor plate 48 and the expander suction port 4 a is opened. Accordingly, the high pressure working fluid from the radiator 3 is drawn into the suction side space 43 a of the expander working chamber 43 through the expander suction port 4 a. Thereafter, the expander suction port 4 a is exposed completely when the shaft 81 rotates about 30°. On the other hand, as shown in FIGS. 7A and 7B, the expander suction port 4 a starts being blocked by the rotor plate 48 when the shaft 81 rotates about 125°, and the expander suction port 4 a is blocked completely when the shaft 81 rotates about 140°. Thereby, the suction process is completed.

Thereafter, as shown in FIG. 7C, the volumetric capacity of the suction side space 63 a of the expander working chamber 63 increases gradually as the shaft 81 rotates, and thereby the working fluid is expanded and a torque is applied to the shaft 81. The torque applied to the shaft 81 is used as the power for the compressor 6. The shaft 81 rotates 360° and the expander piston 42 passes the top dead center, so that the suction side space 43 a of the expander working chamber 43 shifts to the discharge side space 43 b. Then, the shaft 81 makes one rotation, so that the expanded working fluid is discharged from the discharge side space 63 b toward the evaporator 5 through the expander discharge port 4 b.

Next, the operation of the compressor 6 will be described. The shaft 81 is rotated by the power recovered by the expander 4. With the rotation of the shaft 81, the compressor piston 62 also rotates, and thereby the compressor 6 is driven.

As shown in FIG. 6C and FIG. 7A, the compressor suction port 6 a is opened when the shaft 81 rotates about 105°, and the low pressure working fluid from the evaporator 5 is drawn into the suction side space 63 a of the compressor working chamber 63 through the compressor suction port 6 a. Then, the compressor piston 62 rotates further and the suction side space 63 a of the compressor working chamber 63 is brought into communication with the compressor discharge port 6 b, and thereafter the compressor piston 62 passes the top dead center. Thereby, the suction side space 63 a of the compressor working chamber 63 shifts to the discharge side space 63 b, so that the volumetric capacity of the discharge side space 63 b of the compressor working chamber 63 decreases gradually as the shaft 81 rotates. This compresses the working fluid in the discharge side space 63 b of the compressor working chamber 63, increasing the pressure of the working fluid. When the pressure of the working fluid in the discharge side space 63 b of the compressor working chamber 63 becomes higher than the pressure of the working fluid in the discharge chamber 66 a, the working fluid in the discharge side space 63 b presses and opens the discharge valve 68 and is discharged toward the main compressor 2 through the compressor discharge port 6 b.

<Actions and Effects of the Present Embodiment>

As described above, in the present embodiment, the expander suction port 4 a is opened during the period of time when θ=0° to about 140°, and the expander suction port 4 a is closed during the period of time when θ=about 140° to 360°. On the other hand, the compressor suction port 6 a is closed during the period of time when θ=about 95° to about 105°, and the compressor suction port 6 a is opened during the periods of time when θ=0° to about 95° and θ=about 105° to 360°. Moreover, the compressor discharge port 6 b is in communication with the compressor discharge port 6 b through the compressor working chamber 63 during the period of time when θ=about 85° to about 95°. That is, the expander suction port 4 a is closed after the compressor suction port 6 a is brought into communication with the suction side space 63 a of the compressor working chamber 63, and the expander suction port 4 a is opened before the suction side space 63 a of the compressor working chamber 63 is brought into communication with the compressor discharge port 6 b.

As described in the section <Operation of refrigeration cycle apparatus>, since, at the start of the refrigeration cycle apparatus 1, the main compressor 2 is started in the state in which the second bypass valve 94 is opened and the compressor upstream valve 71 is closed, high pressure-low pressure differences occur between the working fluid in the flow passage on the side of the suction mouth of the expander 4 and the working fluid in the flow passage on the side of the discharge mouth of the expander 4, and between the working fluid in the flow passage on the side of the suction mouth of the compressor 6 and the working fluid in the flow passage on the side of the discharge mouth of the compressor 6, respectively. In other words, the flow passage of the fluid machine 8A upstream of the expander suction port 4 a through the suction pipe 82 and the flow passage of the fluid machine 8A upstream of the compressor suction port 6 a through the suction pipe 84 are filled with the high pressure working fluid.

In the present embodiment, since the fluid machine 8A is configured as described above, at least one of the expander suction port 4 a and the compressor suction port 6 a always is opened and the high pressure working fluid always flows into at least one of the suction side space 43 a of the expander working chamber 43 and the suction side space 63 a of the compressor working chamber 63 no matter what angular position the shaft 81 of the fluid machine 8A takes at the start of the refrigeration cycle apparatus. Moreover, it is after the expander suction port 4 a is opened that the compressor suction port 6 a is brought into communication with the compressor discharge port 63 b through the compressor working chamber 63. Therefore, no matter in what state the fluid machine 8A is stopped, a torque for rotating the shaft 81 can be generated in one or both of the expander 4 and the compressor 6, making it possible for the fluid machine 8A to self-start owing to the pressure of the working fluid.

Specifically, when the shaft 81 is in the range of θ=0° to about 85°, both of the expander suction port 4 a and the compressor suction port 6 a are opened and the high pressure working fluid flows into the suction side space 43 a of the expander working chamber 43 and the suction side space 63 a of the compressor working chamber 63. Thus, a torque is generated in each of the expander 4 and the compressor 6.

When the shaft 81 is in the range of θ=about 85° to about 95°, the compressor suction port 6 a is opened but is in communication with the compressor discharge port 6 b through the compressor working chamber 63, and the working fluid leaks from the compressor suction port 6 a to the compressor discharge port 26 b. Thus, no torque is generated in the compressor 6. However, since the expander suction port 4 a is opened and the high pressure working fluid flows into the suction side space of the expander working chamber 63, a torque is generated in the expander 4.

When the shaft 81 is in the range of θ=about 95° to about 105°, the compressor suction port 6 a is closed and no torque is generated in the compressor 6, but the expander suction port 4 a is opened and the high pressure working fluid flows into the suction side space 63 a of the compressor working chamber 63. Thus, a torque is generated in the compressor 6.

When the shaft 81 is in the range of θ=about 105° to about 140°, both of the expander suction port 4 a and the compressor suction port 6 a are opened and the high pressure working fluid flows into the suction side space 43 a of the expander working chamber 43 and the suction side space 63 a of the compressor working chamber 63. Thus, a torque is generated in each of the expander 4 and the compressor 6.

When the shaft 81 is in the range of θ=about 140° to 360°, the expander suction port 4 a is closed and no torque is generated in the expander 4, but the compressor suction port 6 a is opened and the high pressure working fluid flows into the suction side space 63 a of the compressor working chamber 63. Thus, a torque is generated the compressor 6.

As described above, in the present embodiment, the fluid machine 8A, which has no driving device, can self-start without fail at the start of the refrigeration cycle apparatus 1 owing only to the pressure of the working fluid. Therefore, the reliability of the refrigeration cycle apparatus 1 can be increased.

Embodiment 2

Next, a fluid machine 8B according to Embodiment 2 of the present invention will be described with reference to FIG. 8 and FIG. 9. In the present embodiment, the same components as those in Embodiment 1 are designated by the same reference numerals, and the descriptions thereof are omitted. In addition, since a refrigeration cycle apparatus using the fluid machine 8B is the same as the refrigeration cycle apparatus 1 shown in FIG. 1, the description thereof also is omitted.

<Configuration of Fluid Machine>

The fluid machine 8B of the present embodiment is different from the fluid machine 8A of Embodiment 1 in that the suction pipe 84 is connected to the second closing member 66, and the compressor 6 is a fluid pressure motor compressor and does not have the discharge valve 68 (see FIG. 2). That is, the compressor 6 increases the pressure of the working fluid without changing the volume of the working fluid.

Specifically, in the second closing member 66, the compressor suction port 6 a is provided so as to be exposed only to the suction side space 63 a of the compressor working chamber 63 and the compressor discharge port 6 b is provided so as to be exposed only to the discharge side space 63 b of the compressor working chamber 63. Both of the compressor suction port 6 a and the compressor discharge port 6 b extend in the axial direction of the shaft 81. Moreover, a suction passage 6 c that brings an upper end of the compressor suction port 6 a into communication with the suction pipe 84 and a discharge passage 6 d that brings an upper end of the compressor discharge port 6 b into communication with the discharge pipe 85 are formed in the second closing member 66.

More specifically, the compressor suction port 6 a and the compressor discharge port 6 b extend from a vicinity of the compressor partition member 64 so as to be gradually away from the inner circumferential surface of the compressor cylinder 61. Outer edges of the compressor suction port 6 a and the compressor discharge port 6 b (edges on a side of the inner circumferential surface of the compressor cylinder 61) each are formed in an arc shape that coincides with the outer circumferential surface of the compressor piston 62 when the compressor piston 62 is present at the top dead center. That is, the compressor suction port 6 a is completely closed by the compressor piston 63 only during a short period of time after the compressor piston 62 is present at the top dead center, and the compressor discharge port 6 b is completely closed by the compressor piston 63 only during a short period of time before the compressor piston 62 is present at the top dead center.

Moreover, in the present embodiment, the relationship between the eccentric orientation of the first eccentric portion 81 b of the shaft 81 and the eccentric orientation of the second eccentric portion 82 b of the shaft 81, and the relationship between the position of the expander partition member 44 and the position of the compressor partition member 64 are the same as in Embodiment 1.

The compressor suction port 6 a and the compressor discharge port 6 b do not necessarily have to be provided in the second closing member 66, and one or both of them may be provided in the first closing member 49.

<Operation of Fluid Machine 8B>

Next, the operation of the fluid machine 8A during the steady operation will be described with reference to FIGS. 10A to 10C and FIGS. 11A to 11C. In these figures, the rotation angle θ of the shaft 81 when the expander piston 42 is present at the top dead center is defined as 0°. Since the operation of the expander 4 is the same as in Embodiment 1, the description thereof is omitted.

As shown in FIG. 10C and FIGS. 11A to 11C, the compressor suction port 6 a is completely closed by the compressor piston 62 when the shaft 81 rotates from the point of 90° to the point of about 95°. After the shaft 81 rotates about 95°, the compressor suction port 6 a is opened gradually and the low pressure working fluid from the evaporator 5 is drawn into the suction side space 63 a of the compressor working chamber 63 through the compressor suction port 6 a. Then, as shown in FIGS. 10A and 11B, the compressor suction port 6 a is closed gradually after the compressor piston 62 rotates about 360°. When the shaft 81 rotates 90° again, the suction process is completed and the suction side space 63 a of the compressor working chamber 63 shifts to the discharge side space 63 b. After the shaft 81 rotates 90°, the compressor discharge port 6 b is opened gradually, and the working fluid in the discharge side space 63 b is discharged toward the main compressor 2 through the compressor discharge port 6 b. Such extrusion of the working fluid by the compressor piston 62 increases the pressure of the working fluid. The compressor discharge port 63 b is closed gradually after the shaft 81 rotates about 300°, and is completely closed by the compressor piston 62 when the shaft 81 rotates from the point of about 85° to the point of about 90°.

<Actions and Effects of the Present Embodiment>

In the present embodiment, the expander suction port 4 a is opened during the period of time when θ=0° to about 140°, and the expander suction port 4 a is closed during the period of time when θ=about 140° to 360°, as described above. In contrast, the compressor suction port 6 a is closed during the period of time when θ=90° to about 95°, and the compressor suction port 6 a is opened during the periods of time when θ=0° to 90° and θ=about 95° to 360°. That is, the expander suction port 4 a is closed after the compressor suction port 6 a is brought into communication with the suction side space 63 a of the compressor working chamber 63, and the expander suction port 4 a is opened before the compressor suction port 6 a is closed.

As described in the section <Operation of refrigeration cycle apparatus>, since, at the start of the refrigeration cycle apparatus 1, the main compressor 2 is started in the state in which the second bypass valve 94 is opened and the compressor upstream valve 71 is closed, high pressure-low pressure differences occur between the working fluid in the flow passage on the side of the suction mouth of the expander 4 and the working fluid in the flow passage on the side of the discharge mouth of the expander 4, and between the working fluid in the flow passage on the side of the suction mouth of the compressor 6 and the working fluid in the flow passage on the side of the discharge mouth of the compressor 6, respectively. In other words, the flow passage of the fluid machine 8A upstream of the expander suction port 4 a through the suction pipe 82 and the flow passage of the fluid machine 8A upstream of the compressor suction port 6 a through the suction pipe 84 are filled with the high pressure working fluid.

In the present embodiment, since the fluid machine 8A is configured as described above, at least one of the expander suction port 4 a and the compressor suction port 6 a always is opened and the high pressure working fluid always flows into at least one of the suction side space 43 a of the expander working chamber 43 and the suction side space 63 a of the compressor working chamber 63 no matter what angular position the shaft 81 of the fluid machine 8A takes at the start of the refrigeration cycle apparatus 1. Therefore, no matter in what state the fluid machine 8A is stopped, a torque for rotating the shaft 81 can be generated in one or both of the expander 4 and the compressor 6, making it possible for the fluid machine 8A to self-start owing to the pressure of the working fluid.

Specifically, when the shaft 81 is in the range of θ=0° to 90°, both of the expander suction port 4 a and the compressor suction port 6 a are opened and the high pressure working fluid flows into the suction side space 43 a of the expander working chamber 43 and the suction side space 63 a of the compressor working chamber 63. Thus, a torque is generated in each of the expander 4 and the compressor 6.

When the shaft 81 is in the range of θ=90° to about 95°, the compressor suction port 6 a is closed and no torque is generated in the compressor 6, but the expander suction port 4 a is opened and the high pressure working fluid flows into the suction side space 63 a of the compressor working chamber 63. Thus, a torque is generated in the compressor 6.

When the shaft 81 is in the range of θ=about 95° to about 140°, both of the expander suction port 4 a and the compressor suction port 6 a are opened and the high pressure working fluid flows into the suction side space 43 a of the expander working chamber 43 and the suction side space 63 a of the compressor working chamber 63. Thus, a torque is generated in each of the expander 4 and the compressor 6.

When the shaft 81 is in the range of θ=about 140° to 360°, the expander suction port 4 a is closed and no torque is generated in the expander 4, but the compressor suction port 6 a is opened and the high pressure working fluid flows into the suction side space 63 a of the compressor working chamber 63. Thus, a torque is generated in the compressor 6.

As described above, in the present embodiment, the fluid machine 8A, which has no driving device, can self-start without fail at the start of the refrigeration cycle apparatus 1 owing only to the pressure of the working fluid. Therefore, the reliability of the refrigeration cycle apparatus 1 can be increased.

Other Embodiments

In the embodiments mentioned above, the rotor plate 48 constitutes the drawing control mechanism in which the expander suction port 4 a is opened and closed as the shaft 81 rotates. However, the drawing control mechanism of the present invention is not limited to this and drawing control mechanisms with various structures can be employed. For example, a drawing control mechanism with the structure disclosed in Patent Literature 1 may be employed, or a drawing control mechanism in which an arc groove is provided in an upper surface of the first eccentric portion 81 b of the shaft 81 and a communication groove that brings the arc groove into communication with the suction side space 43 a of the expander working chamber 43 is provided in the lower surface of the first closing member 49 may be employed.

INDUSTRIAL APPLICABILITY

The present invention surely can realize the self-starting of the fluid machine. The present invention is useful particularly for refrigeration cycle apparatuses using the fluid machine as a power recovery system. 

1. A fluid machine comprising: an expander that expands a working fluid drawn through an expander suction port and discharges the working fluid through an expander discharge port so as to recover power from the working fluid; a compressor that increases a pressure of the working fluid drawn through a compressor suction port and discharges the working fluid through a compressor discharge port; and a shaft that couples the expander to the compressor so that the compressor is driven by the power recovered by the expander, wherein the expander suction port and the compressor suction port are opened and closed as the shaft rotates, and the expander suction port is opened during a period of time when the compressor suction port is closed, and the compressor suction port is opened and maintained out of communication with the compressor discharge port during a period of time when the expander suction port is closed.
 2. The fluid machine according to claim 1, wherein the shaft has a first eccentric portion for the expander and a second eccentric portion for the compressor, the compressor includes a compressor piston into which the second eccentric portion is fitted, a compressor cylinder accommodating the compressor piston, and a compressor partition member partitioning a compressor working chamber formed between the compressor piston and the compressor cylinder into a suction side space and a discharge side space, and within a period of time when the expander suction port is opened, the compressor piston passes a top dead center at which a sliding point of the compressor piston sliding on an inner circumferential surface of the compressor cylinder coincides with the compressor partition member.
 3. The fluid machine according to claim 2, wherein the expander includes an expander piston into which the first eccentric portion is fitted, an expander cylinder accommodating the expander piston, and an expander partition member partitioning an expander working chamber formed between the expander piston and the expander cylinder into a suction side space and a discharge side space, and 0.25θo≦βv−βc≦0.75θo is satisfied where, when a rotation direction of the shaft is defined as positive, βc (−180°<βc≦180°) indicates a phase difference of an eccentric orientation of the second eccentric portion with respect to an eccentric orientation of the first eccentric portion, βv (−180°<βc≦180°) indicates a phase difference of a position of the compressor partition member with respect to a position of the expander partition member, and further θo indicates a rotation angle of the shaft during the period of time when the expander suction port is opened.
 4. The fluid machine according to claim 2, wherein the compressor suction port is provided in the compressor cylinder and opens on the inner circumferential surface of the compressor cylinder, and the expander suction port is closed after the compressor suction port is brought into communication with the suction side space of the compressor working chamber, and the expander suction port is opened before the suction side space of the compressor working chamber is brought into communication with the compressor discharge port.
 5. The fluid machine according to claim 4, wherein the compressor further includes a discharge valve for opening and closing the compressor discharge port owing to a pressure of the discharge side space of the compressor working chamber.
 6. The fluid machine according to claim 2, wherein the compressor further includes an inner closing member for closing the compressor working chamber from a side of the expander and an outer closing member for closing the compressor working chamber from a side opposite to the expander, the compressor suction port is provided in the inner closing member or the outer closing member so as to be exposed only to the suction side space of the compressor working chamber, and the expander suction port is closed after the compressor suction port is brought into communication with the suction side space of the compressor working chamber, and the expander suction port is opened before the compressor suction port is closed.
 7. The fluid machine according to claim 6, wherein the compressor discharge port is provided in the inner closing member or the outer closing member so as to be exposed only to the discharge side space of the compressor working chamber.
 8. The fluid machine according to claim 3, wherein the expander further includes a drawing control mechanism for opening and closing the expander suction port as the shaft rotates.
 9. The fluid machine according to claim 8, wherein the expander further includes an inner closing member for closing the expander working chamber from a side of the compressor and an outer closing member for closing the expander working chamber from a side opposite to the compressor, the expander suction port is provided in the inner closing member or the outer closing member so as to penetrate through the inner closing member or the outer closing member, and the drawing control mechanism is a rotor plate that is attached to the shaft so as to rotate while being in contact with a surface of the inner closing member or the outer closing member opposite to the expander working chamber and that has a large diameter portion for blocking the expander suction port and a small diameter portion for exposing the expander suction port.
 10. A refrigeration cycle apparatus using the fluid machine according to claim 1, comprising: a working fluid circuit through which a working fluid circulates, the working fluid circuit including a main compressor for compressing the working fluid, a radiator for radiating heat from the compressed working fluid, the expander for expanding the working fluid that has flowed out of the radiator, an evaporator for evaporating the expanded working fluid, and the compressor for increasing a pressure of the working fluid that has flowed out of the evaporator and supplying the working fluid to the main compressor; and a bypass passage linking a portion between the main compressor and the radiator or a portion between the radiator and the expander to a portion between the evaporator and the compressor in the working fluid circuit. 